The present invention relates to an irrigation system, and, more particularly, an improvement of an irrigation system which continuously supplies water or other liquid to plants or vegetables at a very low rate.
Recently, modern agriculture more often employs an irrigation system adapted to supply water or other liquid such as liquid fertilizer to the root portions of plants or vegetables at a low but continuous rate in the form of droplets of mist in consideration of conservation of water resources and the desireable effect of continuous moistening enjoyed by most plants and vegetables. The conventional irrigation system for this purpose generally comprises a source means of pressurized liquid such as a pump, a head tank, etc. and passage means such as a pipeline system for conducting liquid from said source means to individual irrigation spots, wherein the passage means have small openings for discharging liquid therefrom. In this irrigation system, any desired low rate of continuous supply of liquid will be available by judiciously designing said small openings so that they have a certain required throttling effect. However, since such small openings must generally be greatly throttled so that the overall liquid supply rate remains at a certain necessary minimum value under the condition of continuously operating of the irrigation system, this system has the problems that it is very difficult and expensive to obtain such very small openings having a certain correct required throttling ratio on the one hand and that the very small openings are very liable to blocking or clogging on the other hand.